The present invention relates to a disk device capable of diminishing flutter caused by an air flow created with rotation of a disk.
Information read/write devices using various types of media such as optical disks and magnetic tapes are known. Among them, hard disk drives (HDDs) have become popular as storage devices for computers to such an extent that they are one type of the storage devices indispensable for today's computers. Further, not limited to computers, their application is widening more and more due to the superior characteristics with the advent of moving picture recording/reproducing devices, car navigation systems, removable memories used in digital cameras and so on.
The hard disk drive comprises a magnetic disk for storing data, a head which reads and/or writes data with respect to the magnetic disk, and an actuator for moving the head up to a desired position on the magnetic disk. The actuator is driven by a voice coil motor and is adapted to move pivotally about a pivot shaft, thereby causing the head to move radially over the magnetic disk. As a result, the head makes access to a desired track formed on the magnetic disk and can read and/or write data.
Within a mechanical portion (Hard Disk Assembly (HDA)) sealed hermetically by a base and a top cover in this hard disk drive (HDD), in order to ensure the reliability of the head-disk interface, it is necessary to remove lubricating oil leaking out from the actuator for actuating the magnetic head and also remove fine dust which may be generated due to wear of the drive mechanism. To meet this requirement, a circulation filter for the collection of dust is disposed within the HDA at a position where a pressure difference occurs. As the magnetic disk rotates, an air flow occurs along the outer periphery of the disk and in the disk rotating direction. By passing of this air flow through the circulation filter it is possible to remove dust contained in the air flow.
As the recording track pitch in HDD becomes shorter, a higher tracking accuracy is demanded. However, oscillation of the magnetic disk during rotation of the disk exerts a great influence on the accuracy of tracking operation. Although an air flow is created with rotation of the disk within the HDA, this air flow is allowed to advance smoothly by a flow uniforming wall which is provided in a partially intermittent form along the outer periphery of the disk, thereby suppressing oscillation of the disk caused by the air flow. Therefore, it is preferable that the flow uniforming wall be formed as continuously as possible. But in a place where the circulation filter is disposed, for example in a corner of the HDA, the flow uniforming wall usually becomes discontinuous because there are formed an inlet for admitting the air flow to the circulation filter and an outlet for exit of the air flow from the same filter.
In this connection, an information recording medium driving device described in Patent Document 1 (Japanese Pat. Laid-Open No. Hei 11-73756) includes a flow uniforming wall formed in a corner portion of a casing which houses a disk-like information recording medium therein, the flow uniforming wall functioning to uniform an air flow created along the outer periphery of the information recording medium and in a rotating direction of the same medium, and a circulation filter for collecting dust contained in the air flow which is introduced behind the flow uniforming wall through an inlet opening formed in the flow uniforming wall. An increase of oscillation of a magnetic disk caused by disturbance of the air flow which occurs along the outer periphery of the disk during high-speed rotation of the disk is prevented by adjusting the relation d/L between a corner length L along the outer periphery of the information recording medium and the width d of the inlet opening.